The present invention relates to a centrifugal compressor and, more particularly, it relates to an improvement of the speed increasing gear which is a component of the centrifugal compressor.
Thrust and radial bearings for supporting the end portions of an impeller shaft are attached, independently of the other, to a casing for the speed increasing gear in the case of the conventional centrifugal compressor.
The lubrication oil supply means for the speed increasing gear employed by the conventional centrifugal compressor has been designed to have a spray nozzle attached to the casing of the speed increasing gear and a pipe connected from outside to the spray nozzle wherein lubrication oil is supplied through the pipe and sprayed at the gears through the spray nozzle, or to have a plurality of pinholes formed through that wall of the casing which faces the gear, and a large-diameter hole communicated with the pinholes wherein the lubrication oil is supplied through the large-diameter hole and jetted at the gears through the pinholes.
In the case of the conventional centrifugal compressor, however, it was difficult to stably support the impeller shaft unless both of the radial and thrust bearings were attached to the casing of the speed increasing gear. When arranged so, the clearance between the thrust bearing and collar on the impeller shaft in the axial direction thereof must be adjusted, with the impeller shaft assembled in the casing of the speed increasing gear, and the assembly of these components in a narrow space thus needed so careful attention. In addition, a lot of time and labor was needed in confirming the clearance dimension when these components were held assembled, then dismantling them to adjust the spacer, and assembling them again.
Further, the state of the lubrication oil which was being supplied to the gear was very difficultly confirmed through a narrow window after the whole of the speed increasing gear was assembled. When a trouble was caused, no adjustment could be done unless the casing of the speed increasing gear was dismantled. This needed an assembly and a lot of time and labor again.